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ID:9859259
大小:58.23 KB
页数:10页
时间:2018-05-12
《电气专业毕业设计外文翻译----电力变压器工作原理》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、外文资料翻译PowerTransformerPrinciples1.INTRODUCTIONThehigh-voltagetransmissionwasneedforthecaseelectricalpoweristobeprovidedatconsiderabledistancefromageneratingstation.Atsomepointthishighvoltagemustbereduced,becauseultimatelyismustsupplyaload.Thetransformermakesitpossibleforvar
2、iouspartsofapowersystemtooperateatdifferentvoltagelevels.Inthispaperwediscusspowertransformerprinciplesandapplications.2.TOW-WINDINGTRANSFORMERSAtransformerinitssimplestformconsistsoftwostationarycoilscoupledbyamutualmagneticflux.Thecoilsaresaidtobemutuallycoupledbecausethe
3、ylinkacommonflux.Inpowerapplications,laminatedsteelcoretransformers(towhichthispaperisrestricted)areused.Transformersareefficientbecausetherotationallossesnormallyassociatedwithrotatingmachineareabsent,sorelativelylittlepowerislostwhentransformingpowerfromonevoltageleveltoa
4、nother.Typicalefficienciesareintherange92to99%,thehighervaluesapplyingtothelargerpowertransformers.Thecurrentflowinginthecoilconnectedtotheacsourceiscalledtheprimarywindingorsimplytheprimary.Itsetsupthefluxφinthecore,whichvariesperiodicallybothinmagnitudeanddirection.Theflu
5、xlinksthesecondcoil,calledthesecondarywindingorsimplysecondary.Thefluxischanging;therefore,itinducesavoltageinthesecondarybyelectromagneticinductioninaccordancewithLenz’slaw.Thustheprimaryreceivesitspowerfromthesourcewhilethesecondarysuppliesthispowertotheload.Thisactionisk
6、nownastransformeraction.3.TRANSFORMERPRINCIPLESWhenasinusoidalvoltageVpisappliedtotheprimarywiththesecondaryopen-circuited,therewillbenoenergytransfer.TheimpressedvoltagecausesasmallcurrentIθtoflowintheprimarywinding.Thisno-loadcurrenthastwofunctions:(1)itproducesthemagneti
7、cfluxinthecore,whichvariessinusoidallybetweenzeroandφm,whereφmisthemaximumvalueofthecoreflux;and(2)itprovidesacomponenttoaccountforthehysteresisandeddycurrentlossesinthecore.Therecombinedlossesarenormallyreferredtoasthecorelosses.Theno-loadcurrentIθisusuallyfewpercentofther
8、atedfull-loadcurrentofthetransformer(about2to5%).Sinceatno-loadtheprimarywindingac
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